The three-acre formal garden at Wethersfield designed by Evelyn Poehler draws visitors from near and far, dazzling spectators with architecture, statuary, colors, lines, and different blooms and beauties throughout the year. While every turn shows a breathtaking view, a focal point of the garden has been the large hedge of white cedar trees, known as an allée. French for "path," this landscaping term refers to a border of trees forming an avenue that focuses on a highlight of a garden. In the case of the Wethersfield Allée, the centerpiece was a fountain topped with the bronze "Naiad" statue designed by Carl Milles.

The Arborvitae Allée at Wethersfield was planted in 1957. At its height, this wall of white cedar measured 24 feet tall and 190 feet long, making it one of the most sizable allées in the world. Wethersfield Estate Manager Kevin Malloy remembers Mr. Stillman referring to the Allée as "the great green wall of Dutchess County." Pietro Annigoni, the Italian portrait painter who frescoed two rooms of the Main House, made an oil sketch of the allée. This sketch served as the inspiration for his "Wethersfield Dreamscape." (Both paintings are displayed in the living room of the House.)

After half a century of elegance, the soft cedar wood of the Arborvitae Allée began to break down. In the winter of 2011, early snows and an ice storm fell several trees. The remaining trees also suffered damage. Rather than working against time and the natural lifespan of the original Arborvitae trees, and to ensure the enjoyment of many generations to come, preparation was made to plant a new allée.

​In October 2015, the old Allée was taken down, and by Spring 2016, 88 new young trees had been planted. These Arborvitae will grow to the grandeur of the original Allée, and preserve the beauty of Wethersfield Garden for years to come.